Pharmaceutical Composition Comprising Botulinum Toxin for Treating Knee Joint Pain by Saphenous Nerve Entrapment

ABSTRACT

There is provided a pharmaceutical composition comprising botulinum toxin and a pharmacologically acceptable carrier for treating pain in the knee joint caused by saphenous nerve entrapment. The composition of the present invention is for subcutaneous injection above the medial side of the knee.

TECHNICAL FIELD

The present invention relates to a pharmaceutical composition comprisingbotulinum toxin and a pharmacologically acceptable carrier for treatingpain in the knee joint by saphenous nerve entrapment. In use, thecomposition of the present invention is injected subcutaneously abovethe medial side of the knee.

BACKGROUND ART

As is well known, a knee joint consists of an inside and an outside. Ithas often been believed that the knee pain is caused by problems of theinside of the joint. However, receptors, which function to transportpain, are more present around the joint than the inside of the joint.Furthermore, autoradiography reveals that the level of knee injury isnot necessarily directly proportional to the level of pain in the knee.With age, a man typically has injury to the inside of the joint whilethe outside of the joint undergoes various changes.

The saphenous nerve is a nerve that transfers the pain of the medialside of the knee. The entrapment of the nerve also causes pain in theknee. Although the saphenous nerve entrapment can be identified byelectroneuromyography, etc., the saphenous nerve is oftentimes notentrapped when the nerve is in a rest state. As such, it is virtuallyimpossible to diagnose the entrapment by electroneuromyography when thenerve is in the rest state. (See, Schon L C, Baxter D E. Neuropathies ofthe foot and ankle in athletes, Clin Sports Med. 1990 April; 9(2):489-509, Mens J M. Pseudoarthritis of the knee caused by compressionneuropathy of the saphenous nerve, Ned Tijdschr Geneeskd, 1987 Jul. 11;131(28): 1215-8, Morganti C M, McFarland E G, Cosgarea A J. Saphenousneuritis: a poorly understood cause of medial knee pain, J Am AcadOrthop Surg. 2002 March-April; 10(2): 130-7). The saphenous nerveentrapment is a condition that occurs frequently. However, a drug whichefficiently treats the pain associated therewith has not been developed.

The anaerobic, gram positive bacterium Clostridium botulinum produces abotulinum toxin. Such toxin causes a neuroparalytic illness in humansand animals known as botulism. The effects of botulism typically appearabout 18 to 36 hours after eating foods infected with Clostridiumbotulinum spores. The botulinum toxin can apparently pass through thelining of the gut and attack the peripheral motor neurons.

Botulinum toxins have been used in clinical settings for the treatmentof neuromuscular disorders characterized by hyperactive skeletalmuscles. Botulinum toxin type A has been approved by the U.S. Food andDrug Administration for the treatment of blepharospasm, strabismus andhemifacial spasm. Non-type A botulinum toxin serotypes apparently havelower potency and/or shorter duration of activity than botulinum toxintype A. Clinical effects of peripheral intramuscular botulinum toxintype A are usually seen within one week of injection. A typical durationof symptomatic relief from a single intramuscular injection of botulinumtoxin type A averages about three months

Although techniques for treating pain through the use of botulinum toxinhave been developed, the botulinum toxin used in the prior art focusedon the effect of the toxin on the acetylcholine per se.

For example, US patent publication 2003/0224019 is directed to the useof botulinum toxin type B for treating pain caused by nerve entrapment.It specifies that the botulinum toxin type B is injected into an areawhere nerve entrapment occurs. This may also include an area impingingthe nerve itself or near the nerve. In the publication, the duration ofeffect in patients responding to MYOBLOC™ treatment has been observed tobe between 12 and 16 weeks at a dosage of 5,000 units or 10,000 units.

The use of botulinum toxin type A has been disclosed in US patentpublication 2004/028704. In that publication, the botulinum toxin type Ais utilized for treating pain caused from carpal tunnel syndrome.Further in that publication, the botulinum toxin type A is injected intomuscles of the hand and/or wrist, or the carpal tunnel along the mediannerve.

US patent publication 2004/038874 discloses that the botulinum toxintreats pain by blocking acetylcholine and/or neurotransmitter ratherthan directly affecting the receptors. However, it does not specify thearea to be injected.

Furthermore, WO 2001/78760 describes a method for treating pain throughperipheral administration of botulinum toxin to a patient who isexperiencing a non-muscle disorder related pain. However, the botulinumtoxin in that method is not injected into a certain treatment areaidentified by a physical scientific examination. It is rather randomlyinjected into a non-specified area, thereby exhausting acetylcholine andcontrolling pain by a chemically mediated response. Thus, such method isnot intended to treat a specific disease.

Although the prior art references describe that the pain could betreated by using the botulinum toxin, they fail to teach or suggesttreating the pain in the knee joint rapidly and effectively throughinjecting a lower amount of botulinum toxin. Currently, there is a needfor a drug which can be applied effectively to treat the pain in theknee joint.

DISCLOSURE OF INVENTION Technical Problem

The objective of the present invention is to provide a pharmaceuticalcomposition that can treat pain in the knee joint by saphenous nerveentrapment in a more rapid and effective manner, while comprising asmaller amount of active ingredient.

The inventor of the present invention found that the pain in the kneejoint caused by saphenous nerve entrapment can be treated more rapidlyand effectively by injecting the present composition, which includes thebotulinum toxin and a pharmacologically acceptable carrier, into thearea having many abnormal hypersensitive receptors. Such area can beidentified by palpating the subcutaneous fascia above the medial side ofthe knee.

Therefore, the present invention provides a pharmaceutical compositioncomprising botulinum toxin and a pharmacologically acceptable carrierfor treating pain in the knee joint caused by saphenous nerveentrapment.

More specifically, the present invention provides a pharmaceuticalcomposition comprising botulinum toxin and a pharmacologicallyacceptable carrier for treating pain in the knee joint caused bysaphenous nerve entrapment, in which such composition is forsubcutaneous injection above the medial side of the knee.

Preferably, the composition of the invention is injected into asubcutaneous fascia having densely close hypersensitive receptors andlocated at the saphenous nerve-dominating area above the medial side ofthe knee.

According to the present invention, a smaller amount of botulinum toxinis injected into the knee so that the pain caused by saphenous nerveentrapment thereat can be treated more rapidly and the treating effectcan be maintained for at least 4 weeks, preferably 16 weeks, and morepreferably 32 weeks.

Preferably, the composition of the present invention comprisingbotulinum toxin can be injected to multiple points on the subcutaneousfascia located at a hand's breadth above the medial side of the knee.The terms “hand's breadth” above the medial side of the knee signifies adistance of about 15 to 25 cm above the medial side of the knee in whichthe multiple points of injections are defined, which distance may bevaried depending on the patient's height and the like.

The area having many abnormal receptors to which the present compositionis injected into can be identified by feeling the skin, tenderness of apatient, skin thickness, etc. in palpating the patient.

Specifically, if there is severe pain when pinching the skin where thesaphenous nerve passes underneath, it is believed that saphenous nerveentrapment may cause pain in the knee medial side upon moving.Therefore, pinching the skin area where the saphenous nerve passesunderneath can identify certain region that is abnormally hypersensitiveto acetylcholine etc. so that botulinum toxin can be injected thereinto.Thus, the possibility of controlling pain by injecting botulinum toxinto the sub-cutaneous fascia around the knee has been unknown in the artuntil the development of the present invention.

Technical Solution

The present invention provides a pharmaceutical composition comprisingbotulinum toxin and a pharmacologically acceptable carrier for treatingpain in the knee joint caused by saphenous nerve entrapment.

By botulinum neurotoxin (or botulinum toxin) is meant in the presentapplication a botulinum neurotoxin complex (whether of type A, B, C, D,E, F or G) as well as a high purity botulinum neurotoxin (whether oftype A, B, C, D, E, F or G). Botulinum toxin type A includes all typesof botulinum toxin type A, including A1, A2 and A3.

By botulinum neurotoxin complex (whether of type A, B, C, D, E, F or G)should be understood in the present application a botulinum neurotoxin(whether of type A, B, C, D, E, F or G) associated with at least anothernon-toxic protein.

By high purity botulinum neurotoxin (whether of type A, B, C, D, E, F orG) is meant, in the present application, botulinum neurotoxin (whetherof type A, B, C, D, E, F or G) outside from complexes including at leastanother protein. In other words, a high purity botulinum neurotoxin(type A, B, C, D, E, F or G) does not contain significant quantities ofany other Clostridium spp derived protein than botulinum neurotoxin(type A, B, C, D, E, F or G).

The present invention is directed to a method for controlling pain byremoving saphenous nerve entrapment which induces pain around the kneejoint, and not for treating pain which occurs inside of the joint.

As described above, it is believed that botulinum toxin, used in theprior art for treating pain, paralyzes a muscle by inhibiting secretionof acetylcholine. Thus, it decreases the motility of alpha and gammamoving fibers, thereby controlling the pain. In contrast, the botulinumtoxin, a neurophilic material included in the composition of the presentinvention, causes an immediate nerve reflex. Specifically, it cause suchnerve reflex on a hypersensitive acetylcholine receptor and other painreceptors etc., which are present in fascia and muscle around the nerveinducing the entrapment, upon its injection to such fascia and muscle.This relaxes the fascia and muscle by normalizing the hypersensitivereceptors. It further controls the pain and improves the motility bynormalizing a receptor (C fiber) that transfers signals for excessivepain.

The secretion of acetylcholine is not crucial for the present invention.It takes ordinarily 3 to 5 days for the botulinum toxin to block thesecretion of acetylcholine. The present invention aims at inducing nervereflex by the neurophilic property of the botulinum toxin. However, thepresent invention can alleviate or remove the pain in a remarkably shorttime even with a smaller amount of the toxin.

Other advantage of the present invention is that the composition of thepresent invention does not disturb the normal secretion of acetylcholinewithout any paralysis of muscles or other soft tissue. In contrast, ifthe botulinum toxin is used in the conventional pain treatment method,there are several side effects to be considered (e.g., luxation oftemporomandibular joint in injecting the toxin to the muscle of thejoint). For example, the hypersensitive receptor responds as if manyacetylcholine acts thereon even when a small amount of acetylcholine ispresent.

The conventional botulinum toxin injection is administered deeply in amuscle in order to block secretion of acetylcholine, thereby paralyzingthe muscle. In contrast, the present invention does not significantlyconsider whether or not acetylcholine secretes. It administers the toxininjection in order to block the response of the hypersensitive receptoron secretion of a small amount of acetylcholine, to which the normalreceptor does not respond. Therefore, the present invention achieves itsdesired objective by using a small amount of botulinum toxin and it isnot necessary to inject the toxin formulation deeply into the muscle forparalyzing the muscle as in the prior art. Such mechanism and methodhave not been suggested in any of the publications or documents.

As described above, US patent publication 2003/0224019 discloses thatthe botulinum toxin type B can be used for treating pain. Further, USpatent publication 2004/028704 describes that the pain derived fromcarpal tunnel syndrome is treated by using the botulinum toxin type A.However, these publications do not suggest any treatment of knee jointpain caused by saphenous nerve entrapment.

Preferably, the pharmaceutical composition of the present inventioncomprising the botulinum toxin is injected into the subcutaneous fascia,which has densely close hypersensitive receptors, located at thesaphenous nerve-dominating area above the medial side of the knee.However, the injected area of the prior art is a tissue impinging thenerve, an interstitial area around the nerve or a connecting tissuearound the nerve.

The area to be injected by the pharmaceutical composition of the presentinvention is the overall area being controlled by a nerve, regardless ofthe existence of the nerve itself, where the hypersensitive receptorsexist. The composition of the present invention is preferablysimultaneously injected into multiple points on the subcutaneous fasciaregardless of the entrapment point. US patent publication 2003/0224019,on the other hand, injects the botulinum toxin only where nerveentrapment occurs.

The injected area of the muscles of the hand and/or wrist, or the carpaltunnel along the median nerve described in US patent publication2004/028704, also differ from that of the present invention. This isbecause the publication does not disclose or suggest the crucial featureof the present invention, namely, the injected area which is the overallarea being controlled by a nerve where the hypersensitive receptorsexist. This is regardless of the existence of the nerve itself.

Although US patent publication 2004/038874 does not specify an injectedarea, it is nonetheless different from the present invention. Morespecifically, it treats the pain by blocking acetylcholine, aneurotransmitter, rather than directly affecting the receptors as in thepresent invention.

Furthermore, WO 2001/78760 suggests that the pain might be alleviated ortreated by administering botulinum toxin to the joint or subcutaneouslyaround the joint. However, the publication does not disclose the use ofthe botulinum toxin to treat the knee pain caused by saphenous nerveentrapment. Furthermore, the botulinum toxin in this method is injectedrandomly into non-specified area, and not a certain treatment areaidentified by a physical scientific examination. Hence, it exhaustsacetylcholine and controls pain by a chemically mediated response. Also,it does not suggest the significance of hypersensitive receptor control,and further fails to disclose that the toxin has to be injected into thearea where the hypersensitive receptors are densely located.

More particularly, the publication does not disclose or suggest thetechnical feature of the present invention whereby the physicalscientific examination or instrument is used to find an area. It furtherdoes not disclose where the hypersensitive receptors are densely locatedand dominated by saphenous nerve above the knee medial side. Thatpublication also does not disclose that a small amount of botulinumtoxin is injected multiply into the subcutaneous fascia of the area toinduce nerve reflex and thereafter the disappearance of the receptorhypersensitivity is confirmed by pinching the skin.

The pharmaceutical composition of the present invention, which comprisesa significantly smaller amount of botulinum toxin than the dosage usedin the prior art, shows a superior effect for alleviating or treatingthe pain in the knee.

In one particular embodiment of the invention, the botulinum toxin typeA that is injected into a subject in need thereof, which is aningredient of the pharmaceutical composition of the present invention,is shown to have an excellent effect. For example, such superior effectis achieved even in 60 LD₅₀ units of dosage, which is a greatly smalleramount than that in the prior art. In the instant application, unlessspecified otherwise, one LD₅₀ unit of botulinum toxin means the medianlethal intraperitoneal dose in a group of 18 to 20 female Swiss-Webstermice weighing about 20 grams each.

More specifically, US patent publication 2003/0224019 utilizing thebotulinum toxin type B for treating the pain caused by nerve entrapmentdescribes that the duration of effect in patients responding to MYOBLOC™treatment has been observed to be between 12 and 16 weeks at dosage of5,000 units or 10,000 units. It should be noted herein that 20 to 200LD₅₀ units of botulinum toxin type A utilized in one embodiment of thepresent invention correspond to approximately 300 to 3,000 units ofbotulinum toxin type B (1,000 units of botulinum toxin type B correspondto approximately 60 LD₅₀ units of botulinum toxin type A utilized in thepresent invention).

Therefore, US patent publication 2003/0224019 would involve theinjection of 300 or 600 LD₅₀ units of botulinum toxin type A. Thisclearly means that the present invention injects a significantly smalleramount of botulinum toxin type A than that of the publication.

In addition, the present invention relieves the pain in the knee muchmore quickly than the prior art. Unlike the prior art wherein the painis relieved 2 to 3 days after injection, the composition of the presentinvention can remove the pain immediately after the injection of thecomposition. This means that the hypersensitivity of the receptor ischanged.

Most of the injected subjects were confirmed to have disappearedhypersensitivity. In case that the cause for producing thehypersensitivity is more complicated in some patients (e.g., secondaryhyperalgesia), such change of the receptor hypersensitivity ismeaningless. That is, if such patients again show pain several daysafter injection, then there is a secondary reason for inducing receptorhypersensitivity. This means that the composition of the presentinvention has no effect on the pain. This is for the following reason. Asmall amount of botulinum toxin temporarily changes the hypersensitivityof the receptor, which makes the receptor normalized. If the normalizedreceptor is affected by a secondary reason, then the normalized receptorbecomes hypersensitive again.

Unless such situation occurs, however, the hypersensitivity of thereceptor may be maintained for a substantial period or permanently.Since the mechanism of the pain treatment is to change thehypersensitivity of the receptor, the receptor having the changedhypersensitivity is not affected by the retention effect or actionperiod of the drug.

The hypersensitive acetylcholine receptor responds to acetylcholine of1/1000 or less of the normal amount of acetylcholine, thereby inducingcontracture of the muscle. The composition of the present inventionintends to render the abnormal receptor that responds to such smallamount of acetylcholine changed directly. That is, the composition ofthe present invention functions not to block secretion of acetylcholineor other chemicals. Rather, it normalizes the hypersensitive receptorthat responds to the chemicals sensitively regardless of theirsecretion, and that transfers to the nerve the incorrect information asif large amounts of chemicals are secreted even when small amounts weresecreted. Thus, it is not necessary to use the botulinum toxin in largedosage, which paralyzes the muscle.

As explained above, the pharmaceutical composition of the presentinvention comprising the botulinum toxin has a superior effect foralleviating or treating the knee pain by removing the hypersensitivityof the abnormal receptor.

The knee joint pain by saphenous nerve entrapment results from the nerveentrapment caused by entrapping the saphenous nerve in the state wheremuscle or fascia around saphenous nerve is contractured. The pain ofknee medial side is felt when walking and disappears during rest. Thepresent invention elucidated that the botulinum toxin normalizes theseveral hypersensitive receptors, including the acetylcholine receptor,by directly affecting such receptors. This induces nerve reflex and asmaller amount of the toxin can be used to treat the knee joint pain ina remarkably short time by reducing the contracture of muscle and fasciaentrapping or stimulating saphenous nerve branch.

The inventor of the present invention investigated the pain alleviatingeffect of botulinum toxin by injecting the toxin to patients who sufferfrom the knee joint pain. As a result, it could be confirmed that theknee joint pain of the patients was significantly decreased in a shortperiod after injecting the toxin.

When the pharmaceutical composition of the present invention is used inactuality, unit dosage forms which are suitable for injection areformulated and administered according to the conventions of thepharmaceutical field.

The suitable injection formulation, in addition to botulinum toxin asthe pharmacologically active agent, may contain one or morepharmacologically non-active conventional carrier mediums (e.g.,excipients such as starch, lactose, carboxymethylcellulose, kaolin, andthe like; stabilizers such as albumin, gelatin, and the like; binderssuch as alcohol, glucose, arabic gum, tragacanth gum and the like;disintegrants such as starch, dextrine, sodium alginate, and the like;and lubricants such as talc, stearic acid, magnesium stearate, liquidparaffin, and the like).

For example, the injection formulation of the present invention can beprepared by mixing botulinum toxin obtained by purifying cultures ofClostridium botulinum. This is through using a known method with albuminsolution as a stabilizer and lactose as a excipient in a physiologicalsaline solution.

The dosage of the composition according to the present invention dependson various factors such as patient's degree of knee pain, time of onsetof knee pain, age, etc. However, for an average adult, a total of about20 to 200, preferably about 30 to 100, and more preferably about 40 to70 LD₅₀ units (e.g., about 60 to 70 LD₅₀ units) of the botulinum toxintype A are injected into multiple points on the subcutaneous fasciaaround saphenous nerve having the hypersensitive receptors. A singletreatment produces the sufficient effect for removing the pain. However,if the skin pinched by the fingers is thick and the pain is serious, thebotulinum toxin can be injected in larger amounts beyond the abovespecified units.

As for the dosage of various types of botulinum toxins (e.g., B, C, D,E, F and G) that can be used in the present invention, a person skilledin the art could easily determine the appropriate dosage of each type ofthe botulinum toxin based on that of the botulinum toxin type A. Forexample, when figuring out the suitable dosage of the botulinum toxin Baccording to the dosage of the botulinum toxin type A of the presentinvention, it should be noted herein that about 300 to 3,000 units ofbotulinum toxin type B correspond to about 20 to 200 LD₅₀ units ofbotulinum toxin type A. This is based on the fact that 1,000 units ofbotulinum toxin type B correspond to approximately 60 LD₅₀ units ofbotulinum toxin type A of the present invention.

The pain of the patient may be deemed to have been treated sufficientlyby normalization of the hypersensitive receptor (1) if the paindisappears when the skin is pinched immediately after injection of thecomposition and (2) if the thickly seized region of the skin disappears.

The present invention is further described with the following example.This example is intended only to illustrate the present invention andshould not be construed as limiting the present invention in any way.

ADVANTAGEOUS EFFECTS

The composition comprising the botulinum toxin according to the presentinvention has a superior effect of more rapidly alleviating or treatingthe knee joint pain even in a smaller dosage so that the composition canbe utilized in treating pain in the knee joint.

BEST MODE FOR CARRYING OUT THE INVENTION

The effect of the pharmaceutical composition of the present inventionfor treating the knee joint pain caused by the saphenous nerveentrapment was investigated through the following test.

Example 1

Double-blinded placebo-controlled clinical trial was carried out for 89patients of chronic knee pain. This was to compare the effect ofbotulinum toxin type A injection with that of a physiological salinesolution in Chronic Pain Center of Cha hospital located in Seoul, SouthKorea.

The botulinum toxin type A injection used in the test was prepared bydissolving Dysport (trademark), which is commercially available fromIpsen Limited (England), comprising 500 units of botulinum toxin type Awith 20% albumin solution (0.625

) and lactose (2.5 mg) in the physiological saline solution of 18 cc.

The injected areas were identified by Pinch-roll test where the skinfascia governed by the saphenous nerve is pinched and rolled by thefinger. The specified areas having the hypersensitive receptors werefound to be approximately 5 to 12 areas per patient knee. The specifiedareas were further pinched to confirm more sensitive points and theabove prepared formulation was injected to the points in a dosage of 5or 10 units of the toxin type A per injection point. The total dosageper treatment was about 60 units based on Dysport.

The group, to which botulinum toxin type A was injected, did not show asignificant difference from the control group with respect to painlevel, arthritis severity on X-ray photograph, etc. before theinjection. Based on 10 cm-Visual analogue scale (VAS) with 10representing the pain score before the treatment, the control groupshowed a slight decrease from about 8.1 to about 6.03 three weeks afterinjection of the saline solution. Meanwhile, the pain was remarkablyimproved from 7.35 to 4.59 in the botulinum toxin type A injected group.As such, it was observed that knee extension, which is a major parameterin joint pain and arthritis of the aged, was significantly improved.

TABLE 1 Difference of VAS after end of treatment Control botulinum toxintype A group p value Baseline 8.10 ± 2.16 7.35 ± 2.44 NS After 1 week6.75 ± 2.64 5.83 ± 2.45 NS After 3 weeks 6.03 ± 2.35 4.59 ± 2.69 <0.05

TABLE 2 Difference of flexion contracture after end of treatment Controlbotulinum toxin type A group p value Baseline 17.1 ± 6.50 13.4 ± 6.54 NSAfter 1 week 16.9 ± 6.30 12.1 ± 5.71 <0.05 After 3 weeks 17.2 ± 5.3612.1 ± 6.30 <0.05

As seen from Table 2, the control group showed no knee extension threeweeks after being injected with the saline solution. Statistically,however, the botulinum toxin type A group was found to show significantknee extension.

INDUSTRIAL APPLICABILITY

As evidenced by the above tests, the composition comprising thebotulinum toxin according to the present invention has a superior effectof more rapidly alleviating or treating the knee joint pain even in asmaller dosage so that the composition can be utilized in treating painin the knee joint.

1. A pharmaceutical composition comprising botulinum toxin and apharmacologically acceptable carrier for treating knee joint pain causedby saphenous nerve entrapment, the composition being for subcutaneousinjection above the medial side of the knee.
 2. The composition of claim1 wherein the composition comprises about 20 to 200 LD₅₀ units of thebotulinum toxin.
 3. The composition of claim 1 wherein the compositionis injected into a sub-cutaneous fascia, which has densely closehypersensitive receptors, located at the saphenous nerve-dominating areaabove the medial side of the knee.
 4. The composition of claim 1 whereinthe botulinum toxin is a botulinum toxin type A.
 5. The composition ofclaim 1 wherein the effect of treating the knee joint pain ispersistently maintained at least for 4 weeks.